Four people have been arrested in Sliven after officers from Bulgaria's organised crime agency raided an illegal lab where they were making methamphetamine. The operation ran from September 30.

It shut down a group that had been making and selling synthetic drugs. All four suspects were caught inside the lab itself.

Searches turned up vessels, lab equipment, precursor chemicals and materials used to make synthetic drugs, including red phosphorus, iodine, bases and acids. Police seized more than 4.5kg of finished methamphetamine, along with mobile phones, electronic scales and other items now part of the investigation. They also found 2,000 euros in cash, as well as British pounds.

Prosecutors have opened a pre-trial case, overseen by the Sliven district prosecutor's office. The investigation is ongoing.